The Annotation And Semantic Information Representation Of Accuracy Feature For Products

The parts' information integration is one of the key technologies in CAD/CAM. The core of the current CAD system is a solid modeling device, and it only provides mathematical accuracy definitions, which can not express all useful information for CAPP, such as technical requirements, roughness, and tolerance information. The accuracy information is only dots or symbols in CAD. In that model there is no relation between geometric data and technical information, including roughness and tolerances. They have no engineering semantics. These symbolic accuracy information can not be used to support the following work, and make it difficult to achieve real integration in CAD, CAPP and CAM.The paper does some research on geometric modeling technology and accuracy information based on feature. Data structure models of roughness and tolerance are proposed. Semantic representations of three-dimensional are given. User interfaces of surface roughness, form and position tolerances are designed. Through human-computer interaction, 3D design of accuracy features is completed. It is convenient to manage accuracy feature integrated information by establishing property sheets. Furthermore, the frame of part's feature and accuracy information integration is put forward, that is, attaching the accuracy features to some geometric factors in order to express all integrated information in the same document. Using XML/RDF, the accuracy feature-model can be used in the exchange of information among 3D-CAD heterogeneous systems by the RDF-neutral document. The ultimate document can be saved with integrated engineering information and can provide some services for the following CAPP and CAM.The programs have been proved correct and feasible through coding, debugging and testing and have realized above-mentioned functions successfully.